Synthesis of Expandable Fluorine Mica from Talc

Hiroshi Tateyama1, Satoshi Nishimura1, Kinue Tsunematsu1, Kazuhiko Jinnai1, Yasuo Adachi1 and Mitsuru Kimura2
1 Government Industrial Research Institute, Kyushu, Shuku-machi, Tosu city Saga prefecture, 841, Japan
2 CO-OP Chemicals Co. Ltd., 1-23-3, Chiyoda-ku, Tokyo, 102, Japan

Abstract: Expandable fluorine micas were synthesized using talc and Na2SiF6 at 800°C for 2 hours in air, nitrogen, argon, and under vacuum. Gaseous SiF4, generated from Na2SiF6, and the resultant amorphous sodium silicofluoride formed during the reaction between talc and Na2SiF6 below 900°C are taking active part in the formation of expandable micas because the intensity of the 12.5 Å reflection of expandable micas decreases as the gas flow increases in the furnace. Expandable micas seem to be formed by the transformation from talc taking place without the entire disruption of the original atomic arrangement. This takes place with the loss of one Mg2+ from an octahedral site and by the intercalation of every two Na+ into the interlayer site of talc. Infrared absorption and thermal analyses show that expandable micas include a small amount of OH in their structures.

Key Words: Expandable mica • Fluorine • Intercalation • Synthesis • Talc

Clays and Clay Minerals; April 1992 v. 40; no. 2; p. 180-185; DOI: 10.1346/CCMN.1992.0400207
© 1992, The Clay Minerals Society
Clay Minerals Society (www.clays.org)